The present invention relates to a liquid non-aqueous dispersion having a copolymer dispersed in a silicone oil, and a process for producing such a dispersion.
Various types of polymers have been used as one of base materials of cosmetics for the purpose of providing cosmetics with such functions as water resistance, oil resistance and adhesion to the skin and making cosmetics keep long. For example, high-molecular weight polymers such as polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl acetate, acrylic ester-based resins, nitrocellulose, alkyd resins, polyamide resins, methoxyethylene/maleic anhydride copolymer and alkanolamine solution of acrylic resins have been used as a base material of cosmetics such as makeup cosmetics, hair cosmetics, nail cosmetics and basic cosmetics.
Cosmetics containing these polymers are indeed improved in durability, but since the coating film formed on the human bodies by application of the cosmetics containing these polymers becomes a continuous film in which the polymer chains are intertwined with each other without a special disign, these cosmetics have the problem that they are rather awkward to be applied by users because the cosmetics give the users such an unpleasant feeling that the human bodies are pulled by the coating film formed. Thus, it was hardly possible to increase the polymer content in the cosmetic formulations, so that a cosmetic material excellent in long-keeping quality has not been obtained.
Under these circumstances, development of a polymer useful for a cosmetic material that can provide cosmetics having good feeling of use and excellent long-keeping quality has been desired.
Use of silicone-acrylic resins as such a polymer has been proposed as a solution to the above problem, and many researches have been made for the improvement of spread, removal of rough feeling and other disagreeable qualities of cosmetics by taking advantage of slip properties of the silicone component.
For instance, JP-A-2-247110 tries to satisfy both requirements for durability and good feeling of use of cosmetics by compounding a silicone-acrylic graft polymer. According to this method, however, when cosmetics blended with the polymer are applied, the coating film formed on the surface of the human body becomes a continuous film in which the polymer chains are intertwined with each other because the polymer used is the one which has been synthesized by a solution polymerization technique. Therefore, feeling of use of these cosmetics was still unsatisfactory, and there was also a restriction on the amount of polymer that can be compounded.
JP-A-8-269332 proposes to blend in cosmetics a non-aqueous resin dispersion prepared by dispersing an acrylic polymer in a hydrophobic medium such as silicone oil by using a silicone-based dispersant resin. In this case, however, as the dispersion is produced by a two-step polymerization method using a large quantity of a high-molecular weight silicone-based dispersant resin which has been previously produced by polymerization, the product assumes a state of solution in which the silicone moiety of the silicone-based dispersant resin is dissolved in a hydrophobic medium, and the obtained dispersion does not become a perfect dispersion system and is highly viscous. Further, since the coating film formed after application of cosmetics is a continuous film in which silicone segments of the silicone moiety of the silicone-based dispersant resin are similarly intertwined with each other, feeling of use of cosmetics is not improved.
Thus, for a material of cosmetics, it is desirable to blend such a polymer dispersion that polymer chains existed on the surfaces of the polymer particles are not intertwined with each other and polymer particles stand in a two dimensional array on the surface of the human body as a film when applying the cosmetics, but there has yet been available no polymer dispersion that can meet the requirement for providing cosmetics with good feeling of use.
Accordingly, an object of the present invention is to provide a polymer dispersion capable of offering cosmetics which have the above-mentioned properties, good water resistance, oil resistance and adhesive qualities to help make-up last longer, can be applied with no resistance, and give good sense of use without causing a disagreeable feeling that the surface of the human body after application of cosmetics is pulled by the coating film formed.
It is also an object of the invention to provide the polymer dispersion in the form of a liquid non-aqueous preparation.